Typically, optical emitters with a provision for optical output (power or flux) control using optical feedback are configured as a discrete emitter and a discrete optical detector. Such devices can be used as sources in linear optical couplers, as accurately controlled optical sources for meteorology applications, and in medical and industrial applications for absorption and reflection measurements.
In fabricating such devices, the emitter and detector are commonly placed on separate substrates because of the dissimilarity in materials and manufacturing processes--most detectors are fabricated from silicon while the emitters are gallium arsenide (GaAs) based. To obtain optical feedback, the radiation from the emitter is optically coupled back to the detector through an optical cavity.
By having the emitter and detector as discrete components, the cost of manufacturing the devices remains high. Two substrates are required in addition to the connections between the devices and outside circuitry. It is therefore desirable to provide an alternative device that offers lower fabrication costs.